Detecting apparatus, power receiving apparatus, power transmitting apparatus, and contactless power supply system

ABSTRACT

There is provided a detecting apparatus including one or a plurality of magnetic coupling elements that include a plurality of coils, and a detector that measures an electrical parameter related to the one or plurality of magnetic coupling elements or to a circuit that at least includes the one or plurality of magnetic coupling elements, and determines from a change in the electrical parameter whether a foreign matter that generates heat due to magnetic flux is present. In the one or plurality of magnetic coupling elements, the plurality of coils are electrically connected such that magnetic flux produced from at least one or more of the plurality of coils and magnetic flux produced from remaining coils of the plurality of coils have approximately opposing orientations.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of U.S. patentapplication Ser. No. 13/790,981, filed Mar. 8, 2013, which claims thebenefit of priority from prior Japanese Priority Patent Application JP2012-057537 filed in the Japan Patent Office on Mar. 14, 2012, theentire content of which is hereby incorporated by reference.

BACKGROUND

The present disclosure relates to a magnetic coupling element thatmagnetically couples with another magnetic coupling element or foreignmatter, and to an apparatus (magnetic coupling apparatus) and system(magnetic coupling system) utilizing such a magnetic coupling element.

More particularly, the present disclosure relates to a detectingapparatus, a power receiving apparatus, a power transmitting apparatus,and a contactless power supply system configured to detect the presenceof foreign matter (such as metal, a magnetized body, or magnet) whichmay generate heat due to magnetic flux between a contactless powersupplying apparatus and an electronic device constituting a contactlesspower supply system.

Recently, increasing attention is being given to power supply systemsthat supply power (transfer power) to a consumer electronics (CE)device, such as a mobile phone or portable music player, for example, ina contactless manner (referred to as contactless power supply systems orcontactless power transfer systems, for example). With such systems,charging is initiated not by inserting (connecting) the connector of anAC adapter or other power supply apparatus into a CE device, but ratherby simply placing an electronic device (the secondary device) onto acharging tray (the primary device). In other words, a terminalconnection between the electronic device and the charging tray isunnecessary.

Electromagnetic induction is established as a technique for supplyingpower in a contactless manner as above. Meanwhile, contactless powersupply systems using a technique called magnetic resonance whichutilizes the resonance phenomenon have been gaining attention recently.

Contactless power supply systems using magnetic resonance areadvantageous in that the principle of the resonance phenomenon may beutilized to transfer power between devices separated by greaterdistances than those of electromagnetic induction. Additionally, thereis an advantage in that the transfer efficiency (power supplyefficiency) does not fall significantly even if the axis alignmentbetween the power source (transmitter coil) and power recipient(receiver coil) is somewhat poor. However, magnetic resonance-basedsystems and electromagnetic induction-based systems are alike in thatboth are contactless power supply systems (magnetic coupling systems)utilizing a power source (transmitter coil; a magnetic coupling element)and a power recipient (receiver coil; a magnetic coupling element).

Meanwhile, one important element in contactless power supply systems isthe thermal regulation of foreign matter, such as metals, magnetizedbodies, and magnets, which may generate heat due to magnetic flux. Ifforeign matter becomes interposed in the gap between the transmittercoil and the receiver coil when supplying power in a contactless manner,there is a risk of causing the foreign matter to generate heat due tothe magnetic flux passing through that foreign matter. This risk is notlimited to electromagnetic induction-based or magnetic resonance-basedsystems. Such heat generation in foreign matter may lead to currentsbeing produced in a foreign metal due to the magnetic flux passingthrough the foreign metal (eddy currents, current loops, circularcurrents), or to hysteresis loss being produced in a foreign magnetizedbody or foreign magnet due to the magnetic flux passing through theforeign magnetized body or foreign magnet.

A large number of techniques that detect foreign metal by adding aforeign matter detection system to a contactless power supply systemhave been proposed for such thermal regulation. For example, techniquesusing an optical sensor or a temperature sensor have been proposed.However, detection methods that use sensors may be costly in the case ofa broad power supply range, as with magnetic resonance-based systems.Moreover, use of a temperature sensor, for example, may imposeadditional design constraints on the transmitting and receiving devices,since the output results from the temperature sensor will depend on itssurrounding thermal conductivity.

Thus, there have been proposed techniques that determine the presence offoreign metal by looking at changes in parameters (such as current andvoltage) when a foreign metal comes between the transmitter andreceiver. With such techniques, it is possible to curtail costs withoutimposing design or other constraints.

For example, JP 2008-206231A proposes a method of detecting foreignmetal according to the modulation rate (information on amplitude andphase changes) during communication between the transmitter andreceiver, while JP 2001-275280A proposes a method of detecting foreignmetal according to eddy current loss (foreign matter detection accordingto DC-DC efficiency).

SUMMARY

However, the techniques proposed in JP 2008-206231A and JP 2001-275280Ado not take into account the effects of a metal housing at the receiver.Consider the case of charging a typical portable device. It is highlyprobably that some kind of metal (such as a metal housing or metalcomponents) is used in the portable device, and thus it is difficult toclearly determine whether a change of parameters is due to the effectsof the metal housing or components, or due to the presence of foreignmetal. To take JP 2001-275280A as an example, it is indeterminatewhether eddy current loss occurs because of the metal housing of theportable device, or because foreign metal is present between thetransmitter and receiver. In this way, it can hardly be said that thetechniques proposed in JP 2008-206231A and JP 2001-275280A are able toaccurately detect foreign metal.

Being devised in light of the above circumstances, an embodimentaccording to the embodiment of the present disclosure detects foreignmatter in close proximity to a detector coil (in other words, a magneticcoupling element) without providing an additional sensor, andfurthermore improves detection accuracy.

According to an embodiment of the present disclosure, there is provideda detecting apparatus including one or a plurality of magnetic couplingelements that include a plurality of coils, and a detector that measuresan electrical parameter related to the one or plurality of magneticcoupling elements or to a circuit that at least includes the one orplurality of magnetic coupling elements, and determines from a change inthe electrical parameter whether a foreign matter that generates heatdue to magnetic flux is present. In the one or plurality of magneticcoupling elements, the plurality of coils are electrically connectedsuch that magnetic flux produced from at least one or more of theplurality of coils and magnetic flux produced from remaining coils ofthe plurality of coils have approximately opposing orientations.

According to an aspect of the present disclosure, it is possible torealize significant improvement regarding issues such as magnetic fluxleakage from a magnetic coupling element, change in the electricalproperties (electrical parameters) of a magnetic coupling element due toexternal factors, and unwanted noise occurring in a magnetic couplingelement.

According to at least one aspect of the present disclosure, it ispossible, without providing an additional sensor, to detect foreignmatter which is in close proximity to a magnetic coupling element andwhich may generate heat due to magnetic flux, and furthermore greatlyimprove detection accuracy.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic circuit diagram accompanying an explanation of Qfactor measurement used as an example of foreign metal detectionaccording to an embodiment of the present disclosure;

FIG. 2 is a diagrammatic exterior illustration of a contactless powersupply system according to the first embodiment of the presentdisclosure;

FIG. 3 is a block diagram illustrating an exemplary configuration of acontactless power supply system according to the first embodiment of thepresent disclosure;

FIGS. 4A to 4C are circuit diagrams illustrating exemplaryconfigurations of a resonant circuit;

FIG. 5 is a schematic diagram of an exemplary diagrammatic configurationof a transmitter coil and a receiver coil in a contactless power supplysystem according to the first embodiment of the present disclosure;

FIG. 6A and FIG. 6B are explanatory diagrams illustrating an exemplarydetailed configuration of a detector coil and receiver coil according tothe first embodiment of the present disclosure, where FIG. 6A is anexemplary perspective view configuration and FIG. 6B is an exemplaryplan view configuration of the detector coil and receiver coil in thecase where the difference between the inner dimension of the detectorcoil and the inner dimension of the receiver coil is −4 mm;

FIG. 7A and FIG. 7B are plan views illustrating an exemplary detailedconfiguration of a detector coil and receiver coil according to thefirst embodiment of the present disclosure, where FIG. 7A illustrates anexemplary plan view configuration of the detector coil and receiver coilin the case where the difference between the inner dimension of thedetector coil and the inner dimension of the receiver coil is 0 mm, andFIG. 7B is an exemplary plan view configuration of the detector coil andreceiver coil in the case where the difference between the innerdimension of the detector coil and the inner dimension of the receivercoil is +4 mm;

FIG. 8A and FIG. 8B are plan views illustrating an exemplary detailedconfiguration of a detector coil and receiver coil according to a firstcomparative example, where FIG. 8A illustrates an exemplary detailedconfiguration of the detector coil and receiver coil in the case wherethe difference between the inner dimension of the detector coil and theinner dimension of the receiver coil is −4 mm, and FIG. 8B is anexemplary detailed configuration of the detector coil and receiver coilin the case where the difference between the inner dimension of thedetector coil and the inner dimension of the receiver coil is 0 mm;

FIG. 9 is a graph of examples illustrating to what degree the detectorcoil Q factor changes depending on the presence or absence of a receivercoil in the case of modifying the inner dimension of the detector coil;

FIG. 10A is a diagrammatic cross-section view regarding a spiral-shapedcoil and the distribution of magnetic field lines produced from thatcoil, while FIG. 10B is a diagrammatic cross-section view regarding afigure 8-shaped coil according to an embodiment of the presentdisclosure and the distribution of magnetic field lines from that coil;

FIG. 11A is a waveform diagram illustrating an example of a waveform ofvoltage (voltage waveform) produced in an LC resonator (resonantcircuit) including a detector coil and a resonant capacitor C3 in thecase where a spiral-shaped detector coil is disposed inside the receivercoil illustrated in FIG. 8A, while FIG. 11B is a waveform diagramillustrating an example of a waveform of voltage (voltage waveform)produced in an LC resonator including a detector coil and a resonantcapacitor C3 in the case where a figure 8-shaped detector coil isdisposed inside the receiver coil illustrated in FIG. 6B;

FIG. 12 is a graph illustrating an example of the difference in thepower supply efficiency of a contactless power supply system accordingto whether or not a foreign matter detecting apparatus is present;

FIG. 13A is a performance mapping illustrating exemplary foreign metaldetection accuracy for the case of using a figure 8-shaped coil as adetector coil, while FIG. 13B is a performance mapping illustratingexemplary foreign metal detection accuracy for the case of using aspiral-shaped coil as a detector coil;

FIG. 14 is a plan view illustrating an exemplary configuration of afigure 8-shaped detector coil according to a first modification of thefirst embodiment of the present disclosure;

FIG. 15 is a plan view illustrating an exemplary configuration of asquare grid-shaped detector coil according to the second embodiment ofthe present disclosure;

FIG. 16 is a plan view illustrating an exemplary configuration of asquare grid-shaped detector coil according to a first modification ofthe second embodiment of the present disclosure;

FIG. 17 is a plan view illustrating an exemplary configuration of alattice-shaped detector coil according to the third embodiment of thepresent disclosure;

FIG. 18 is a plan view illustrating an example of a detector coil unitin which two figure 8-shaped detector coils are disposed according tothe fourth embodiment of the present disclosure;

FIG. 19 is a plan view illustrating an example of a detector coil unitin which two figure 8-shaped detector coils are disposed according to afirst modification of the fourth embodiment of the present disclosure;

FIGS. 20A to 20C are explanatory diagrams for exemplary detector coilarrangements according to the fifth embodiment of the presentdisclosure, where FIGS. 20A, 20B, and 20C are plan views illustrating anexample of a receiver coil, an example in which multiple detector coilsare disposed on top of the receiver coil, and an example in which somedetector coils are disposed in the center of the receiver coil,respectively;

FIGS. 21A to 21C are explanatory diagrams for exemplary detector coilarrangements according to the sixth embodiment of the presentdisclosure, where FIGS. 21A, 21B, and 21C are plan views illustrating anexample of a receiver coil and foreign metal, an example in whichmultiple detector coils are disposed on top of the receiver coil, and anexample in which multiple detector coils are additionally disposed ontop of the multiple detector coils in FIG. 21B, respectively; and

FIG. 22A and FIG. 22B are explanatory diagrams for exemplary detectorcoil arrangements according to a first modification of the sixthembodiment of the present disclosure, where FIGS. 22A and 22B are planviews illustrating an example in which multiple detector coils aredisposed on top of the receiver coil, and an example in which multipledetector coils are additionally disposed on top of the multiple detectorcoils in FIG. 22A, respectively.

DETAILED DESCRIPTION OF THE EMBODIMENT(S)

Hereinafter, preferred embodiments of the present disclosure will bedescribed in detail with reference to the appended drawings. Note that,in this specification and the appended drawings, structural elementsthat have substantially the same function and structure are denoted withthe same reference numerals, and repeated explanation of thesestructural elements is omitted.

Hereinafter, the description will proceed in the following order.

-   1. Introductory explanation-   2. First embodiment (example of magnetic coupling element with    figure 8-shaped detector coil)-   3. Second embodiment (example of magnetic coupling element with    square grid-shaped detector coil)-   4. Third embodiment (example of magnetic coupling element with    lattice-shaped detector coil)-   5. Fourth embodiment (example of magnetic coupling element using two    figure 8-shaped detector coils)-   6. Fifth embodiment (example of magnetic coupling element disposing    multiple detector coils on top of receiver coil)-   7. Sixth embodiment (example of magnetic coupling element disposing    multiple detector coils over wide range on top of receiver coil)-   8. Other    <1. Introductory Explanation>

In the present disclosure, there is proposed a magnetic coupling systemthat detects foreign matter on the basis of an electrical parameter fora circuit at a transmitter or a receiver when charging a component suchas a battery in the receiver (secondary device) with power supplied fromthe transmitter (primary device). In a magnetic coupling systemaccording to an embodiment of the present disclosure, an electricalparameter is measured for a circuit in a transmitter or a receiver, thecircuit at least including one or multiple magnetic coupling elementswhich magnetically couple with an external element and which arerealized with multiple coils. The presence of foreign matter in closeproximity to the magnetic coupling element is then determined on thebasis of the electrical parameter measurement results.

Hereinafter, a description will be given using, as an example, the casewhere the above circuit at least including a magnetic coupling elementis a resonant circuit, while in addition, the above electrical parameteris the quality factor (Q factor). The Q factor is an index expressingthe relationship between energy storage and loss, and is typically usedas a factor expressing the sharpness of the resonance peak (in otherwords, the resonance strength) in a resonant circuit.

Note that although the descriptions of the respective embodiments of thepresent disclosure in this specification cite the detection of foreignmetal as an example, the detection of other foreign matter (such asforeign magnetized bodies and foreign magnets) is also similar.

[Q Factor Measurement Principle]

Hereinafter, the principle of Q factor measurement will be describedwith reference to the drawings.

FIG. 1 is a schematic circuit diagram accompanying an explanation of Qfactor measurement used for foreign metal detection according to anembodiment of the present disclosure.

The circuit illustrated in FIG. 1 is an example of a basic circuitlayout (for the case of magnetic coupling) illustrating the principle ofQ factor measurement. The circuit is provided with a signal source 1,which includes an alternating current (AC) power source 2 that producesan AC signal (sine wave) and a resistive element 3, as well as acapacitor 4 and a coil 5. The resistive element 3 is an illustration ofthe internal resistance (output impedance) of the AC power source 2. Thecapacitor 4 and the coil 5 are connected to the signal source 1 so as toform a series resonant circuit (one example of a resonant circuit). Theresonant circuit resonates at a given frequency (the resonant frequency)according to the capacitance value (C value) of the capacitor 4 and theinductance value (L value) of the coil 5.

Although FIG. 1 illustrates a circuit provided with a series resonantcircuit realized with a coil 5 and a capacitor 4, various layouts areconceivable for the detailed configuration, insofar as resonant circuitfunctionality is provided.

If foreign metal, such as a metal fragment, for example, is present nearthe coil 5, the magnetic field lines will pass through the metalfragment, and eddy currents will be produced in the metal fragment. Fromthe perspective of the coil 5, the metal fragment and the coil 5 aremagnetically coupled and it appears as though a resistive load has beenattached to the coil 5, changing the Q factor of the coil (resonantcircuit). Measuring the Q factor thus leads to detection of foreignmetal near the coil 5 (in other words, a magnetically coupled state).

At this point, take V1 to be the voltage across the ends of the coil 5and the capacitor 4 constituting the series resonant circuit (an exampleof voltage applied to a resonant circuit), and take V2 to be the voltageacross the ends of the coil 5. In this case, the Q factor of the seriesresonant circuit is expressed as in Eq. 1, where R is the effectiveresistance value (series resistance value) for the frequency f of thecircuit, L is the inductance value, and C is the capacitance value. WhenV2>>V1, the equation may be approximated as follows.

$\begin{matrix}{Q = {{\frac{1}{R}\sqrt{\frac{L}{C}}} = {\frac{{V\; 2} - {V\; 1}}{V\; 1} \cong \frac{V\; 2}{V\; 1}}}} & (1)\end{matrix}$

In the circuit illustrated in FIG. 1, the voltage V2 is obtained bymultiplying the voltage V1 by a factor of approximately Q. It isestablished that the series resistance value R and the inductance valueL indicated in Eq. 1 change as metal approaches or due to the effects ofeddy currents produced in the metal. For example, if a metal fragmentapproaches the coil 5, the effective resistance value R increases, andthe Q factor drops. In other words, since the Q factor of the resonantcircuit and the resonant frequency change greatly due to the effects ofmetal present in the vicinity of the coil 5, by detecting such change itis possible to detect a metal fragment present near the coil 5.Additionally, such Q factor measurement may be applied to the detectionof foreign metal interposed between a transmitter (primary device) and areceiver (secondary device).

By conducting a foreign metal detection process using changes in the Qfactor discussed above, it is possible to detect foreign metal with highaccuracy for both electromagnetic induction-based systems and magneticresonance-based systems, and have the user remove the detected foreignmetal.

[Overview of Technology According to the Embodiment of PresentDisclosure]

Meanwhile, another conceivable technique involves using a detectorconnected to a circuit including a coil (detector coil) thatelectromagnetically or magnetically couples with an external element tomeasure the Q factor of the circuit using an AC signal at a differentfrequency than the frequency of the AC signal flowing through thetransmitter coil and the receiver coil.

Also, as another example, a configuration in which the above detectorcoil used to measure the Q factor is separate from the transmitter coiland the receiver coil is also conceivable.

By using an AC signal at a different frequency than the frequency of theAC signal flowing through the transmitter coil and the receiver coil, ACsignals for contactless power supply are separable from AC signals for Qfactor measurement, and thus it becomes possible to measure the Q factorwhile contactless power supply is in operation. In addition, accuratedetection of foreign metal or other matter may be conducted even whilecontactless power supply is in operation.

However, the detector coil may be greatly affected by the magnetic flux(lines of magnetic force; a magnetic field) for contactless power supplyin the case of using a typical spiral-shaped coil 5 as the detector coilthat electromagnetically or magnetically couples with an externalelement. As a result, AC signals for Q factor measurement utilized inforeign matter detection may overlap AC signals for contactless powersupply, producing unwanted noise due to the contactless power supply. Asa result, foreign metal detection accuracy may decrease greatly.

Also, the above detector coil is readily affected by the transmittercoil and receiver coil used for contactless power supply, as well as byelements such as magnetic materials and metal inside the electronicdevice housing. Given this issue, if a typical spiral-shaped detectorcoil is packaged in a device such as a contactless power supplyapparatus (hereinafter simply designated “power supply apparatus”) orelectronic device, the Q factor of the detector coil, which is used asthe basis value for determining the presence of foreign metal, maydecrease greatly.

Furthermore, foreign metal detection accuracy may change greatlydepending on the configuration of the power source (transmitter) andpower recipient (receiver) in the contactless power supply system.

In this way, it has been difficult to obtain exact information forforeign matter detection, and the foreign matter detection accuracy hasnot improved. Accordingly, the inventors propose a magnetic couplingelement that improves foreign matter detection accuracy by obtainingmore exact information for foreign matter detection, as well as aforeign matter detecting apparatus using such a magnetic couplingelement.

<1. First Embodiment>

[Exemplary Overall Configuration of Contactless Power Supply System]

FIG. 2 illustrates an exemplary diagrammatic configuration of acontactless power supply system given as a magnetic coupling systemaccording to the first embodiment of the present disclosure, while FIG.3 illustrates an exemplary block configuration of a contactless powersupply system according to the first embodiment of the presentdisclosure.

The contactless power supply system 100 illustrated in FIG. 2 is asystem that transfers (supplies) power in a contactless manner using amagnetic field (in the present embodiment, using magnetic resonance).The contactless power supply system 100 is equipped with a power supplyapparatus 10 (the primary device) and one or multiple electronic devices(secondary devices) given as power recipient devices. Herein, anelectronic device 20A in the form of a mobile phone handset and anelectronic device 20B in the form of a digital still camera are providedas power recipient devices, for example. However, a power recipientdevice is not limited to this example, and may be any electronic deviceable to receive power from the power supply apparatus 10 in acontactless manner.

As illustrated in FIG. 2, for example, the contactless power supplysystem 100 is configured such that power is transferred from the powersupply apparatus 10 to the electronic devices 20A and 20B by placing theelectronic devices 20A and 20B onto or in proximity to a power supplysurface (transmitter surface) S1 of the power supply apparatus 10.Herein, the power supply apparatus 10 has a mat shape (or tray shape)with the surface area of the power supply surface S1 being greater thandevices such as the power recipient electronic devices 20A and 20B, inconsideration of the case of transferring power to multiple electronicdevices 20A and 20B simultaneously or in a time division (successively).

(Exemplary Configuration of Power Supply Apparatus)

As described above, the power supply apparatus 10 is an apparatus (suchas a charging tray) that transfers power to electronic devices 20A and20B using a magnetic field. As illustrated in FIG. 3, for example, thepower supply apparatus 10 is equipped with a power transmittingapparatus 11 that transfers power using power supplied from a powersource 9 external to the power supply apparatus 10. The external powersource 9 may be, for example, an electric utility from which power issupplied via a plug socket, otherwise called a power outlet.

The power transmitting apparatus 11 includes a transmitter 12, ahigh-frequency power generator circuit 13, a detector circuit 14, animpedance matching circuit 15, a controller circuit 16, and a resonantcapacitor (capacitive element) C1, for example. By providing thedetector circuit 14 and the controller circuit 16, the powertransmitting apparatus 11 in this example takes a block configurationenabling the contactless power supply system 100 to conductunidirectional communication using load modulation. However, theconfiguration is not limited thereto in cases where unidirectionalcommunication using a technique other than load modulation orbidirectional communication is considered.

The transmitter 12 includes components such as a transmitter coil(primary coil) L1 discussed later (FIG. 5). The transmitter 12 uses thetransmitter coil L1 and the resonant capacitor C1 to transfer power tothe electronic devices 20A and 20B (specifically, to a receiver 22discussed later) using a magnetic field. Specifically, the transmitter12 includes functionality for emitting a magnetic field (magnetic flux)from the power supply surface S1 towards the electronic devices 20A and20B. A detailed configuration of the transmitter 12 will be discussedlater.

The high-frequency power generator circuit 13 is a circuit that usespower supplied from the power source 9 external to the power supplyapparatus 10 to generate given high-frequency power (an AC signal) forthe purpose of power transfer, for example.

The detector circuit 14 is a circuit that includes functionality fordetecting (demodulating) a modulated signal from a load modulatorcircuit 29 discussed later. The detector circuit 14 supplies detectionresults to the controller circuit 16.

The impedance matching circuit 15 is a circuit that matches impedanceduring power transfer. In so doing, efficiency during power transfer(the transfer efficiency) is improved. Note that, depending on theconfiguration of components such as the transmitter coil L1 and areceiver coil L2 discussed later, or the resonant capacitors C1 and C2,it may also be configured such that the impedance matching circuit 15 isnot provided. Also, if decreased transfer efficiency is not a concern,it may be configured such that the impedance matching circuit 15 is notprovided.

The resonant capacitor C1 is a capacitive element constituting part ofthe transmitter coil L1 of the transmitter 12 as well as the LCresonator (resonant circuit), and is disposed with respect to thetransmitter coil L1 so as to form an electrical series connection,parallel connection, or a combined series and parallel connection. Withan LC resonator including the transmitter coil L1 and the resonantcapacitor C1, resonant operation is realized at a resonant frequency(first resonant frequency) f1 whose frequency is approximately equal ornear that of the high-frequency power generated in the high-frequencypower generator circuit 13. The capacitance value of the resonantcapacitor C1 is also set so as to obtain such a resonant frequency f1.

However, it may also be configured such that the resonant capacitor C1is not provided if the above resonant frequency f1 is realized byresonant operation using a potential difference across the windings inthe transmitter coil L1 or a parasitic capacitance component (straycapacitance component) realized by a potential difference between thetransmitter coil L1 and the receiver coil L2 discussed later. Also, ifdecreased transfer efficiency is not a concern, it may be similarlyconfigured such that the resonant capacitor C1 is not provided.

The controller circuit 16 is a circuit that receives detection resultsfrom the detector circuit 14 and controls components such as thehigh-frequency power generator circuit 13, the impedance matchingcircuit 15, the resonant capacitor C1, and the transmitter 12.

For example, consider the case where foreign metal is detected betweenthe transmitter 12 and the receiver 22 by a foreign matter detectingapparatus 31 discussed later in the electronic devices 20A and 20B. Atthis point, the detection result from the detector circuit 14 changesdue to load modulation conducted in the load modulator circuit 29, alsodiscussed later, in the electronic devices 20A and 20B. For this reason,the controller circuit 16 in the power transmitting apparatus 11 is ableto confirm the presence of foreign metal, making it possible to restrictor stop power transfer under control by the controller circuit 16.Meanwhile, the controller circuit 16 also receives detection resultsfrom the detector circuit 14 and applies pulse-width modulation control(PWM control) to the high-frequency power generator circuit 13 andswitching control to the impedance matching circuit 15, the resonantcapacitor C1, and the transmitter 12. Such control by the controllercircuit 16 also enables automatic control for maintaining a hightransfer efficiency (power supply efficiency).

(Exemplary Configuration of Electronic Device)

Electronic devices such as stationary electronic devices typified bytelevisions or portable electronic devices typified by mobile phones anddigital cameras, including rechargeable batteries, are applicable as theelectronic devices 20A and 20B. The electronic device 20A and theelectronic device 20B are provided with similar functionality withrespect to power supply, and in the description hereinafter, theelectronic device 20A will be described as a representative example.

As illustrated in FIG. 3, for example, the electronic device 20A isequipped with a power receiving apparatus 21 and a load 27 that performsgiven action (action that elicits functionality as an electronic device)on the basis of power supplied from the power receiving apparatus 21.The electronic device 20A is also equipped with a foreign matterdetecting apparatus 31 for detecting the presence of foreign metalbetween (in the gap between) the transmitter 12 and the receiver 22.

Hereinafter, the power receiving apparatus 21 will be described.

The power receiving apparatus 21 includes a receiver 22, a resonantcapacitor (capacitive element) C2, an impedance matching circuit 23, arectifier circuit 24, a voltage stabilizer circuit 25, a controllercircuit 26, a battery 28, and a load modulator circuit 29. By providingthe load modulator circuit 29 and the controller circuit 26, the powerreceiving apparatus 21 in this example takes a block configurationenabling the contactless power supply system 100 to conductunidirectional communication using load modulation. However, theconfiguration is not limited thereto in cases where unidirectionalcommunication using a technique other than load modulation orbidirectional communication is considered.

The receiver 22 includes components such as a receiver coil (secondarycoil) L2 discussed later (FIG. 5). The receiver 22 includesfunctionality for using the receiver coil L2 and the resonant capacitorC2 to receive power transferred from the transmitter 12 in the powersupply apparatus 10. A detailed configuration of the receiver 22 will bediscussed later.

The resonant capacitor C2 is a capacitive element constituting part ofthe receiver coil L2 of the receiver 22 as well as the LC resonator(resonant circuit), and is disposed with respect to the receiver coil L2so as to form an electrical series connection, parallel connection, or acombined series and parallel connection. With an LC resonator includingthe receiver coil L2 and the resonant capacitor C2, resonant operationis realized at a resonant frequency (second resonant frequency) f2 whosefrequency is approximately equal or near that of the high-frequencypower generated in the high-frequency power generator circuit 13 of thepower transmitting apparatus 11. In other words, the LC resonatorincluding the transmitter coil L1 and the resonant capacitor C1 in thepower transmitting apparatus 11 and the LC resonator including thereceiver coil L2 and the resonant capacitor C2 in the power receivingapparatus 21 resonate with each other at approximately equal resonantfrequencies (f1≈f2). The capacitance value of the resonant capacitor C2is also set so as to obtain such a resonant frequency f2.

However, it may also be configured such that the resonant capacitor C2is also not provided if the above resonant frequency f1 is realized byresonant operation using a potential difference across the windings inthe receiver coil L2 or a parasitic capacitance component realized by apotential difference between the transmitter coil L1 and the receivercoil L2. Also, if decreased transfer efficiency is not a concern, it mayalso be configured such that the resonant frequency f2 and the resonantfrequency f1 differ from each other (f2≠f1), and the resonant capacitorC2 is not provided.

The impedance matching circuit 23 is a circuit that matches impedanceduring power transfer, similarly to the impedance matching circuit 15 inthe above power transmitting apparatus 11. Note that, depending on theconfiguration of components such as the transmitter coil L1 and thereceiver coil L2 discussed later, or the resonant capacitors C1 and C2,it may also be configured such that the impedance matching circuit 23 isalso not provided. Also, if decreased transfer efficiency is not aconcern, it may be similarly configured such that the impedance matchingcircuit 23 is also not provided.

The rectifier circuit 24 is a circuit that rectifies the power (ACpower) supplied from the receiver 22 to generate direct current (DC)power. Note that a smoothing circuit (not illustrated) for smoothingrectified power is often provided between the rectifier circuit 24 andthe voltage stabilizer circuit 25 discussed later.

The voltage stabilizer circuit 25 is a circuit that conducts givenvoltage stabilization on the basis of DC power supplied from therectifier circuit 24, and charges the battery 28 or a battery (notillustrated) in the load 27.

The battery 28 stores power in response to being charged by the voltagestabilizer circuit 25, and may be realized using a rechargeable battery(secondary cell) such as a lithium-ion battery, for example. Note thatthe battery 28 may also be omitted in cases where only the battery inthe load 27 is used, for example.

The load modulator circuit 29 is a circuit for applying load modulation,and changes in the power state due to load modulation may be detectedwith the detector circuit 14 in the power transmitting apparatus 11. Inother words, if given the load modulator circuit 29 and the controllercircuit 26 discussed later, it becomes possible to transmit informationin the power receiving apparatus 21 to the power transmitting apparatus11 without providing a special communication apparatus in the electronicdevice 20A.

The controller circuit 26 is a circuit for controlling chargingoperation with respect to the battery 28 or the battery (notillustrated) in the load 27. The controller circuit 26 is also a circuitfor controlling load modulation in the load modulator circuit 29, andapplies control enabling the power transmitting apparatus 11 torecognize that foreign metal has been detected by having changes in thepower state due to such load modulation be detected with the detectorcircuit 14 in the power transmitting apparatus 11. Additionally, in thecase where the foreign matter detecting apparatus 31 discussed later inthe electronic device 20A detects that foreign metal is present betweenthe transmitter 12 and the receiver 22, it is also possible for thecontroller circuit 26 to apply charging control to restrict or stoppower transfer to the power receiving apparatus 21 in the electronicdevice 20A.

Hereinafter, the foreign matter detecting apparatus 31 will bedescribed. The foreign matter detecting apparatus 31 includes a detectorcoil L3, a resonant capacitor C3, a foreign matter detector circuit 32,and a controller circuit 33. As an example, the foreign matter detectorcircuit 32 and the controller circuit 33 may constitute a detector.

The detector coil L3 is an example of a magnetic coupling element fordetecting foreign metal, and is provided separately from the transmittercoil L1 and the receiver coil L2. Further details will be discussedlater (FIGS. 4A, 4B, 4C, 6A, 6B, 7A, 7B, 14-19, 20A, 20B, 20C, 21A, 21B,21C, 22A and 22B).

The resonant capacitor C3 is a capacitor connected to the detector coilL3 in an electrical series configuration (see FIG. 4A), or a capacitorconnected to the detector coil L3 in a combined electrical series andparallel configuration (resonant capacitors C3-1 and C3-2) (see FIGS. 4Band 4C). By connecting the resonant capacitor C3, the detector coil L3resonates at a given frequency f3 (LC resonance).

Note that in the case of computing the Q factor of the LC resonator(resonant circuit) from the voltage ratio as discussed later, it isdesirable to connect at least one resonant capacitor C3 to the detectorcoil L3 in series (see FIGS. 4A, 4B, and 4C). However, in the case ofcomputing the Q factor of the LC resonator with a technique other thanvoltage ratio, such as with a width at half maximum (WHM) method, theresonant capacitor C3 may be connected to the detector coil L3 in anelectrical parallel configuration (not illustrated).

The foreign matter detector circuit 32 is a circuit for measuring the Qfactor of the detector coil L3 or the Q factor of the LC resonatorincluding the detector coil L3 and the resonant capacitor C3 by using anAC signal whose frequency (f3, where f3≠f2 and f3≠f2) differs from thefrequencies (f1 and f2, where f1≈f2) of the AC signals flowing throughthe transmitter coil L1 and the receiver coil L2.

The Q factor of the detector coil L3 or the Q factor of the LC resonatorincluding the detector coil L3 and the resonant capacitor C3 may becomputed by measuring voltage values at the two locations (the voltagevalue V1 and the voltage value V2) illustrated in FIGS. 4A, 4B, and 4Cas described earlier with the foreign matter detector circuit 32, andthen taking their ratio (V2/V1), for example.

Also, if the frequency characteristics related to properties such as theimpedance and admittance are able to be measured with the foreign matterdetector circuit 32, it is also possible to compute the Q factor of thedetector coil L3 or the LC resonator from the ratio of the peakfrequency at which the frequency characteristics reach a peak versus thefrequency width where that peak value is halved (WHM) (thus, peakfrequency/WHM).

Additionally, it is also possible to calculate the Q factor from theratio of the real part versus the imaginary part of the impedance of theresonant circuit. The real part and the imaginary part of the impedancemay be computed using an auto-balancing bridge circuit and a vectorratio detector, for example.

The controller circuit 33 is a circuit that controls the foreign matterdetector circuit 32, while also determining the presence of foreignmetal between (in the gap between) the transmitter 12 and the receiver22 from the measurement results by the foreign matter detector circuit32. The controller circuit 33 is also a circuit for transmitting thedetermination result to the controller circuit 26 of the power receivingapparatus 21. The controller circuit 33 may, for example, compare ameasured Q factor to a threshold value saved in memory (not illustrated)in advance, and determine that foreign metal is present near thedetector coil in the case where the measured Q factor is less than thethreshold value.

[Detailed Exemplary Configuration of Transmitter And Receiver]

FIG. 5 is a schematic illustration of an exemplary diagrammaticconfiguration of the transmitter 12 and the receiver 22 in a contactlesspower supply system according to the first embodiment of the presentdisclosure.

The transmitter 12 includes at least one (in this case, one) transmittercoil L1, and the receiver 22 includes at least one (in this case, one)receiver coil L2. It is possible for the transmitter coil L1 and thereceiver coil L2 to be magnetically coupled to each other. Note that itmay also be configured such that the transmitter 12 and the receiver 22includes one or multiple coils or one or multiple LC resonatorsincluding coils and capacitors in addition to the transmitter coil L1and the receiver coil L2.

These coils (the transmitter coil L1 and the receiver coil L2) are notlimited to being open coils (conductive coils) shaped like conductivewire (material) wound multiple times, but may also be open loops(conductive loops) shaped like conductive wire wound one time.

Furthermore, the coil or loop used as such a conductive coil orconductive loop may be a coil (wound coil) or loop (wound loop) in whichconductive wire is wound, or a coil (patterned coil) or loop (patternedloop) formed by a conductive pattern on a printed substrate (printedcircuit board) or flexible printed substrate (flexible printed circuitboard), for example. Also, it is possible to form such a patterned coiland patterned loop by printing or depositing conductive material, or bymachining a conductive metal plate or sheet, for example.

FIG. 5 simultaneously illustrates an exemplary distribution of magneticfield lines produced from the transmitter coil L1 at a given phase. Asdescribed above, the transmitter coil L1 is a coil for transferringpower using magnetic flux (lines of magnetic force; a magnetic field).In other words, the transmitter coil L1 is a coil for producing magneticflux (lines of magnetic force; a magnetic field). Meanwhile, thereceiver coil L2 is a coil for receiving power from the magnetic flux(lines of magnetic force; a magnetic field) transferred from thetransmitter 12.

[Detailed Exemplary Configuration of Detector Coil]

FIG. 6A and FIG. 6B are illustration of an exemplary detailedconfiguration of the detector coil L3 and the receiver coil L2 accordingto the first embodiment of the present disclosure, where FIG. 6A is anexemplary perspective view configuration and FIG. 6B is an exemplaryplan view configuration (exemplary X-Y plan view configuration).

The receiver coil L2 illustrated in FIG. 6A and FIG. 6B is aspiral-shaped coil. In order to effectively raise the magnetic couplingbetween the transmitter coil L1 and the receiver coil L2, it isdesirable for the transmitter coil L1 and the receiver coil L2 to bespiral-shaped coils, helical coils, or coils with a combined spiral andhelical shape, for example. However, the transmitter coil L1 and thereceiver coil L2 are not limited thereto.

Also, the detector coil L3 illustrated in FIG. 6A and FIG. 6B is afigure 8-shaped coil realized by a combination of a spiral-shaped coilL31 and a spiral-shaped coil L32 that distributes magnetic flux ofapproximately the opposite orientation of the orientation of themagnetic flux from the coil L31. Although details will be discussedlater, if the detector coil L3 is simply a spiral-shaped coil, helicalcoil, or a coil with a combined spiral and helical shape, foreign metaldetection accuracy may greatly decrease. For this reason, it isdesirable for the detector coil L3 to be a coil able to distributemagnetic flux (magnetic field lines; a magnetic field) over a surfacewith approximately opposing orientations, such as a figure 8-shaped,square grid-shaped, or lattice-shaped coil as discussed later.

Although details will likewise be discussed later, using a detector coilwith such a shape yields advantages such as enabling decreased magneticflux leakage from the detector coil, decreased change in the electricalproperties (such as the Q factor and L value) of the detector coil dueto external factors, and a decrease in unwanted noise occurring in thedetector coil. For this reason, it is possible to greatly improveforeign metal detection accuracy.

Furthermore, the coil or loop used as the detector coil L3 may be a coil(wound coil) or loop (wound loop) in which conductive wire is wound, ora coil (patterned coil) or loop (patterned loop) formed by a conductivepattern on a printed substrate (printed circuit board) or flexibleprinted substrate (flexible printed circuit board), for example. Also,it is possible to form such a patterned coil and patterned loop byprinting or depositing conductive material, or by machining a conductivemetal plate or sheet, for example.

Also, while the receiver coil L2 and the detector coil L3 may bedisposed in the same plane, the receiver coil L2 and the detector coilL3 may also be disposed in different planes. However, for the sake ofthe packaging area with respect to the electronic device 20A (20B), inmany cases it is desirable to form the receiver 22 (receiver coil L2)and the detector coil L3 in the same plane. In the example in FIG. 6Aand FIG. 6B, the receiver coil L2 and the detector coil L3 are notdisposed in the same plane for the sake of comparison as illustrated inFIG. 9, discussed later.

Additionally, in FIG. 6A and FIG. 6B, the inner dimension (the dimensionof the innermost perimeter) of the detector coil L3 is smaller than theinner dimension C (the dimension of the innermost perimeter) of thereceiver coil L2, and the outer dimension B (the dimension of theoutermost perimeter) of the detector coil L3 is smaller than the innerdimension C (the dimension of the innermost perimeter) of the receivercoil L2. Although details will be discussed later, such a configurationmaximally raises the foreign metal detection accuracy. Obviously,however, the configuration is not limited thereto in applications whereforeign metal detection accuracy is not demanded.

Note that although FIG. 6A and FIG. 6B compared the inner dimension Aand the outer dimension B along the shorter edge of the figure 8-shapeddetector coil L3 to the inner dimension C along the shorter edge of thereceiver coil L2, the dimensions may also be compared using therespective inner dimensions and outer dimensions along the longer edge(such as the inner dimension A′ along the longer edge of the detectorcoil L3, for example). It is further desirable if the inner dimensionand outer dimension along both the shorter edge and the longer edge ofthe detector coil are smaller than the inner dimensions along both theshorter edge and the longer edge of the receiver coil. Obviously,however, the configuration is not limited thereto in applications whereforeign metal detection accuracy is not demanded.

Additionally, although it is desirable for the detector coil L3 to beelectrically insulated from (i.e., not connected to an electricalcontact point or other element in) the transmitter 12 (transmitter coilL1) and the receiver 22 (receiver coil L2), the configuration is notlimited thereto.

Note that in FIG. 6A and FIG. 6B, magnetic shielding material 41 isdisposed between the housing 40 of the electronic device, and thereceiver coil L2 and detector coil L3. The magnetic shielding material41 is provided for the purpose of decreasing magnetic flux leakage fromthe receiver coil L2 and raising the Q factors of the receiver coil L2and the detector coil L3, but may also be omitted as appropriate. Themagnetic shielding material 41 herein may be realized with magneticmaterial such as ferrite, conductive metal such as metal, or acombination of magnetic material and conductive metal, for example.

FIG. 7A and FIG. 7B illustrate different examples of the differencebetween the inner dimension of the detector coil L3 and the innerdimension of the receiver coil L2 in the exemplary detailedconfiguration of the detector coil L3 and the receiver coil L2 in FIG.6A and FIG. 6B.

FIG. 7A illustrates an exemplary detailed configuration of the detectorcoil L3 and the receiver coil L2 in the case where the differencebetween the inner dimension A of the detector coil L3 and the innerdimension C of the receiver coil L2 is 0 mm. Additionally, FIG. 7Billustrates an exemplary detailed configuration of the detector coil L3and the receiver coil L2 in the case where the difference between theinner dimension A of the detector coil L3 and the inner dimension C ofthe receiver coil L2 is +4 mm.

[Action And Advantages of Contactless Power Supply System]

(1. Summary of Overall Operation)

In the power supply apparatus 10 of the contactless power supply system100, the high-frequency power generator circuit 13 supplies givenhigh-frequency power (an AC signal) for transferring power to thetransmitter coil L1 and the resonant capacitor C1 (LC resonator) in thetransmitter 12. In so doing, a magnetic field (magnetic flux) isproduced in the transmitter coil L1 in the transmitter 12. At thispoint, if an electronic device 20A given as a power recipient (chargingtarget) is placed (or brought near) the top surface (power supplysurface S1) of the power supply apparatus 10, the transmitter coil L1 inthe power supply apparatus 10 and the receiver coil L2 in the electronicdevice 20A come into proximity near the power supply surface S1.

In this way, if a receiver coil L2 is placed near a transmitter coil L1producing a magnetic field (magnetic flux), electromotive force, inducedby the magnetic flux produced from the transmitter coil L1, is producedin the receiver coil L2. In other words, the transmitter coil L1 and thereceiver coil L2 are respectively linked by electromagnetic induction ormagnetic resonance, and a magnetic field is produced. In so doing, power(indicated as the contactless power supply P1 in FIG. 3) is transferredfrom the transmitter coil L1 (primary coil; power supply apparatus 10;transmitter 12) to the receiver coil L2 (secondary coil; electronicdevice 20A; receiver 22). At this point, resonant operation using thetransmitter coil L1 and the resonant capacitor C1 is conducted in thepower supply apparatus 10 (at a resonant frequency f1), while resonantoperation using the receiver coil L2 and the resonant capacitor C2 isconducted in the electronic device 20A (at a resonant frequency f2,where f2≈f1).

Thereupon, AC power received by the receiver coil L2 in the electronicdevice 20A is supplied to the rectifier circuit 24 and the voltagestabilizer circuit 25, and the following charging operation isperformed. Namely, after the AC power is converted into given DC powerby the rectifier circuit 24, voltage stabilization based on the DC poweris performed by the voltage stabilizer circuit 25, and the battery 28 ora battery (not illustrated) in the load 27 is charged. In so doing,charging operation based on power received by the receiver 22 isperformed in the electronic device 20A.

In other words, in the present embodiment, a terminal connection to anAC adapter, for example, is unnecessary when charging the electronicdevice 20A, and charging may be easily initiated (contactless powersupply may be performed) by simply placing the electronic device 20Aonto (or in proximity to) the power supply surface S1 of the powersupply apparatus 10. This leads to a reduced burden on the user.

Meanwhile, in the foreign matter detecting apparatus 31 of theelectronic device 20A, the Q factor of a detector coil L3 or an LCresonator including the detector coil L3 and a resonant capacitor C3 ismeasured using an AC signal whose frequency (f3, where f3≠f2 and f3≠f2)differs from the frequencies (f1 and f2) of the AC signals flowingthrough the transmitter coil L1 and the receiver coil L2. The foreignmatter detecting apparatus 31 is also able to determine the presence offoreign metal between (in the gap between) the transmitter 12 and thereceiver 22 from the magnitude of change in this Q factor.

Subsequently, a determination result by the foreign matter detectingapparatus 31 which indicates the presence or absence of foreign metal istransmitted from the power receiving apparatus 21 in the electronicdevice 20A to the power transmitting apparatus 11 in the power supplyapparatus 10 by a communication technique such as load modulation.

Furthermore, in the case where the foreign matter detecting apparatus 31detects the presence of foreign metal between (in the gap between) thetransmitter 12 and the receiver 22, control for restricting or stoppingpower transfer is applied by the controller circuit 16 in the powertransmitting apparatus 11 or the controller circuit 26 in the powerreceiving apparatus 21, for example. As a result, it may be possible topreemptively avoid heat or fire produced in the foreign metal, as wellas malfunction or damage to the contactless power supply system.

(2. Action of Detector Coil)

Next, action of the detector coil L3 given as a characteristic featureof the present embodiment will be described in detail and in comparisonto comparative examples (examples of the related art).

(2.1 Case of Detector Coil According to Comparative Examples)

FIG. 8A and FIG. 8B are plan views illustrating an exemplary detailedconfiguration of a detector coil and receiver coil according tocomparative examples. FIG. 8A illustrates an exemplary detailedconfiguration (exemplary X-Y plan view configuration) of a detector coilL4 according to a first comparative example and the receiver coil L2, inthe case where the difference between the inner dimension of thedetector coil L4 and the inner dimension of the receiver coil L2 is −4mm. FIG. 8B illustrates an exemplary detailed configuration (exemplaryX-Y plan view configuration) of a detector coil L4 according to a secondcomparative example and the receiver coil L2, in the case where thedifference between the inner dimension of the detector coil L4 and theinner dimension of the receiver coil L2 is 0 mm.

Unlike a detector coil L3 according to an embodiment of the presentdisclosure described earlier, these detector coils L4 are simplespiral-shaped coils.

First, data related to the detector coil Q factor is acquired byapplying electromagnetic field analysis to an analysis model of adetector coil and a receiver coil like those illustrated in FIGS. 8A and8B (see FIG. 9). The graph in FIG. 9 illustrates to what degree the Qfactor of the detector coil L4 changes depending on the presence orabsence of the receiver coil L2 in the case of modifying the innerdimension of the detector coil L4. However, when modifying the innerdimension of the detector coil L4, factors such as the conductive wiretype, thickness, width, and the length of the gap between conductivewires constituting the detector coil L4 are not modified.

FIG. 8A is an exemplary detailed configuration of a detector coil and areceiver coil in the case where the difference between the innerdimension of the detector coil and the inner dimension of the receivercoil is −4 mm in the graph in FIG. 9. Also, FIG. 8B is an exemplarydetailed configuration of a detector coil and a receiver coil in thecase where the difference between the inner dimension of the detectorcoil and the inner dimension of the receiver coil is 0 mm in FIG. 9.

FIG. 9 demonstrates that in the case of using a spiral-shaped detectorcoil L4, the Q factor of the detector coil L4 changes greatly dependingon whether or not the receiver coil L2 is present. In other words, FIG.9 demonstrates that the Q factor of the detector coil L4 decreasesgreatly when the receiver coil L2 is present. This indicates that in thecase of using a spiral-shaped detector coil L4, there is significantmagnetic flux leakage from the detector coil L4, and the electricalproperties (such as the Q factor and L value) of the detector coil L4change greatly due to external factors (such as the metal material ormagnetic material constituting the transmitter coil L1, the receivercoil L2, the magnetic shielding material 41, the power supply apparatus10, and the electronic device 20A (20B)).

Stated differently, FIG. 9 demonstrates that foreign metal detectionaccuracy is greatly decreased in the case of using a spiral-shaped coilas the detector coil. Furthermore, FIG. 9 also demonstrates that as theinner dimension A of the detector coil L4 becomes smaller with respectto the inner dimension C of the receiver coil L2 (for example, if thedifference between the detector coil inner dimension A and the receivercoil inner dimension C becomes less than or equal to 0 mm), the amountof decrease in the Q factor of the detector coil L4 due to the presenceof the receiver coil L2 also becomes smaller (see the right side of FIG.9).

(2.2 Case of Detector Coil According to First Embodiment)

In contrast, in the first embodiment of the present disclosure, a figure8-shaped detector coil L3 is used, as illustrated in FIGS. 6A, 6B, 7Aand 7B. All other parameters are basically the same as those of thefirst comparative example and the second comparative example.

Similarly to the case of the above comparative example, data related tothe detector coil Q factor is acquired by applying electromagnetic fieldanalysis to an analysis model of a detector coil and a receiver coillike those illustrated in FIGS. 6A, 6B, 7A, and 7B (see FIG. 9). FIG. 9illustrates to what degree the Q factor of the detector coil L3 changesdepending on the presence or absence of the receiver coil L2 in the caseof modifying the inner dimension of the detector coil L3. However, whenmodifying the inner dimension of the detector coil L3, factors such asthe conductive wire type, thickness, width, and the length of the gapbetween conductive wires constituting the detector coil L3 are notmodified.

FIG. 9 demonstrates that in the case of using a figure 8-shaped detectorcoil L3, although the Q factor of the detector coil L3 does changeslightly depending on whether or not the receiver coil L2 is present,the magnitude of that change is significantly smaller than in the caseof using the spiral-shaped detector coil L4. In other words, FIG. 9demonstrates that although the Q factor of the detector coil L3 doeschange slightly due to the presence of the receiver coil L2, themagnitude of that change is significantly smaller than in the case ofusing the spiral-shaped detector coil L4. This indicates that for thefigure 8-shaped detector coil L3, there is less magnetic flux leakagefrom the detector coil L3, and the electrical properties (such as the Qfactor and L value) of the detector coil L3 change less due to externalfactors (such as the metal material or magnetic material constitutingthe transmitter coil L1, the receiver coil L2, the magnetic shieldingmaterial 41, the power supply apparatus 10, and the electronic device20A (20B)) compared to the spiral-shaped detector coil L4.

Stated differently, FIG. 9 demonstrates that in the case of using afigure 8-shaped coil as the detector coil, foreign metal detectionaccuracy is greatly improved compared to the case of using aspiral-shaped coil. Furthermore, FIG. 9 also demonstrates that as theinner dimension A of the detector coil L3 becomes smaller with respectto the inner dimension C of the receiver coil L2 (for example, if thedifference between the detector coil inner dimension A and the receivercoil inner dimension C becomes less than or equal to 0 mm), the amountof decrease in the Q factor of the detector coil L3 due to the presenceof the receiver coil L2 also becomes smaller.

In addition, FIG. 9 demonstrates that the Q factor of the detector coilL3 is greatest (maximized) in the case where the difference between thedetector coil inner dimension A and the receiver coil inner dimension Cis −4 mm, and in the case where the difference between the detector coilinner dimension A and the receiver coil inner dimension C is 0 mm. Inother words, FIG. 9 demonstrates that it is desirable for the innerdimension A of the detector coil L3 to be smaller than the innerdimension C of the receiver coil L2.

Also, since the difference in the Q factor of the detector coil L3depending on whether or not the receiver coil L2 is present becomessmaller as the inner dimension A of the detector coil L3 becomes smallerwith respect to the inner dimension C of the receiver coil L2, FIG. 9demonstrates that it is desirable for the outer dimension B of thedetector coil L3 also to be smaller than the inner dimension C of thereceiver coil L2. However, the configuration is not limited thereto inthe case where it is desirable to extend the foreign metal detectionrange even if the foreign metal detection accuracy drops.

(2.3 Distribution of Magnetic Field Lines in Detector Coil)

The distribution of magnetic field lines in a detector coil will now bedescribed with reference to FIGS. 10A and 10B.

FIG. 10A is a diagrammatic cross-section view regarding a spiral-shapedcoil (the detector coil L4, for example) at a given time (phase) and thedistribution of magnetic field lines produced from that coil. FIG. 10Bis a diagrammatic cross-section view regarding a figure 8-shaped coil(the detector coil L3, for example) at a given time (phase) and thedistribution of magnetic field lines from that coil.

As illustrated in FIGS. 10A and 10B, the distribution of magnetic fieldlines differs greatly between a spiral-shaped coil and a figure 8-shapedcoil. The figure 8-shaped coil discussed above is configured to be ableto distribute magnetic flux (magnetic field lines; a magnetic field)over a surface such that the magnetic flux from the two coils (the coilsL31 and L32, for example) constituting the figure 8-shaped coil haveapproximately opposing orientations. As a result, in the figure 8-shapedcoil, magnetic field lines are distributed so as to form a loop insidethe coil. In other words, in the figure 8-shaped coil, the magneticfield lines are less likely to be distributed farther compared to aspiral-shaped coil.

For this reason, using the figure 8-shaped detector coil L3 yields lessmagnetic flux leakage from the detector coil L3, and the electricalproperties (such as the Q factor and L value) of the detector coil L3change less due to external factors (such as the metal material ormagnetic material constituting the transmitter coil L1, the receivercoil L2, the magnetic shielding material 41, the power supply apparatus10, and the electronic device 20A (20B)) compared to the spiral-shapeddetector coil L4.

(2.4 Voltage Produced in LC Resonator)

FIG. 11A illustrates a waveform 45 a of voltage produced in an LCresonator including the detector coil L4 and the resonant capacitor C3by causing actual contactless power supply operation using the powertransmitting apparatus 11 and the power receiving apparatus 21, in thecase where the detector coil L4 is provided inside the receiver coil L2as illustrated in FIG. 8A.

In an actual contactless power supply system 100, voltage values (V1 andV2) are measured at two locations in an LC resonator including thedetector coil L4 and the resonant capacitor C3 using an AC signal whosefrequency (f3, where f3≠f2 and f3 f2) differs from the frequencies (f1and f2, where f1≈f2) of the AC signals flowing through the transmittercoil L1 and the receiver coil L2. The Q factor is then calculated fromthe ratio of these two voltage values.

However, FIG. 11A demonstrates that in the case of using thespiral-shaped detector coil L4, an extremely large voltage unnecessaryfor foreign matter detection is produced due to the contactless powersupply frequencies (f1 and f2). In the example in FIG. 11A, the voltagewaveform 45 a has an effective value of 690 mV, and a peak-to-peak (p-p)value of 2.25 V.

This voltage becomes a large source of unwanted noise when measuringvoltage values at two locations in the LC resonator including thedetector coil L4 and the resonant capacitor C3. In other words, in thecase of using the spiral-shaped detector coil L4, the foreign metaldetection accuracy decreases greatly due to this unwanted noise.

Meanwhile, FIG. 11B illustrates a waveform 46 a of voltage produced inan LC resonator including the detector coil L3 and the resonantcapacitor C3 by causing actual contactless power supply operation usingthe power transmitting apparatus 11 and the power receiving apparatus21, in the case where the detector coil L3 is provided inside thereceiver coil L2 as illustrated in FIG. 6A.

FIG. 11B demonstrates that, compared to the case of using thespiral-shaped detector coil L4, almost no voltage is produced due to thecontactless power supply frequencies (f1 and f2, where f1≈f2) in thecase of using the figure 8-shaped detector coil L3. In the example inFIG. 11B, the voltage waveform 46 a has an effective value of 27.7 mV,and a peak-to-peak (p-p) value of 390 mV.

In an actual contactless power supply system 100, voltage values aremeasured at two locations in an LC resonator including the detector coilL3 and the resonant capacitor C3 using an AC signal whose frequency (f3,where f3 ≠f1 and f3 f2) differs from the frequencies (f1 and f2) of theAC signals flowing through the transmitter coil and the receiver coil.The Q factor is then calculated from the ratio of these two voltagevalues. In other words, since there is little unwanted noise, it can besaid that using the figure 8-shaped detector coil L3 has a much higherforeign metal detection accuracy than the case of using thespiral-shaped detector coil L4.

Note that in the case where magnetic flux produced from the transmittercoil L1 or the receiver coil L2 passes through a spiral-shaped coil, theexiting magnetic flux changes according to time (phase). Thus,electromotive force attempting to make current flow in a directionopposing such change is induced in the spiral-shaped coil (see Faraday'slaw of induction and Lenz's law).

Meanwhile, in the case where magnetic flux produced from the transmittercoil L1 or the receiver coil L2 passes through a figure 8-shaped coil,magnetic flux respectively passes through the two coils constituting thefigure 8-shaped coil (the coils L31 and L32 in FIG. 6B) in approximatelythe same direction. However, since the two coils constituting the figure8-shaped coil are electrically connected such that their windingdirections differ, the electromotive force produced in the coils canceleach other out in the case where magnetic flux passes through the twocoils in approximately the same direction, and thus electromotive forcelike that of a spiral-shaped coil is not produced when observing thefigure 8-shaped coil overall. For this reason, a figure 8-shaped coilyields the advantage of little unwanted noise as discussed above.

However, if the magnetic flux passing through the two coils constitutinga figure 8-shaped coil greatly differ from each other, a large level ofunwanted noise may be produced, even in a figure 8-shaped coil. In orderto inhibit the production of unwanted noise, it is desirable for thecenter point of the figure 8-shaped coil and the center point of thetransmitter coil L1 or the receiver coil L2 to exist on the same axis.

(2.5 Measured Data)

The results of various measurements made on a contactless power supplysystem 100 according the present embodiment will now be illustrated.

FIG. 12 illustrates the difference in the power supply efficiency of acontactless power supply system 100 according to whether or not aforeign matter detecting apparatus 31 is present. Herein, the detectorcoil L3 in the foreign matter detecting apparatus 31 is disposed insidethe receiver coil L2 in a relationship like that illustrated in FIG. 6Aand FIG. 6B. FIG. 12 demonstrates that there is almost no change in thepower supply efficiency of a contactless power supply system 100according to whether or not a foreign matter detecting apparatus 31 (thedetector coil L3 and the resonant capacitor C3) is present. This isbecause, as discussed earlier, the detector coil L3 has less magneticflux leakage from the detector coil L3, and the electrical properties(such as the Q factor and L value) of the detector coil L3 exhibitlittle change due to external factors (such as the metal material ormagnetic material constituting the transmitter coil L1, the receivercoil L2, the magnetic shielding material 41, the power supply apparatus10, and the electronic device 20A (20B)).

FIG. 13A and FIG. 13B illustratethe foreign metal detection accuracy ofa detector coil.

FIG. 13A is a performance mapping illustrating exemplary foreign metaldetection accuracy for the case of using a figure 8-shaped coil as adetector coil. Note that in FIG. 13A, the Q factor of the detector coilis assumed to be 100% in the case of packaging the detector coil insidethe electronic device 20A.

If a figure 8-shaped detector coil is disposed on top of the transmitter12 (transmitter coil L1) of the power supply apparatus 10, the detectorcoil is somewhat affected by the transmitter 12 (the transmitter coilL1, magnetic material, and internal metal, for example), and thus the Qfactor of the detector coil drops somewhat (Q factor 47 b) compared towhen the power supply apparatus 10 is not present (Q factor 47 a).However, since the drop in the Q factor of the detector coil issignificantly greater in the case where foreign metal is disposed (Qfactor 47 c), foreign metal may be accurately detected.

Meanwhile, FIG. 13B is a performance mapping illustrating exemplaryforeign metal detection accuracy for the case of using a spiral-shapedcoil as a detector coil. Note that in FIG. 13B, the Q factor of thedetector coil is assumed to be 100% in the case of packaging thedetector coil inside the electronic device 20A.

If a spiral-shaped detector coil is disposed on top of the transmitter12 (transmitter coil L1) of the power supply apparatus 10, the detectorcoil is greatly affected by the transmitter 12 (the transmitter coil L1,magnetic material, and internal metal, for example), and thus the Qfactor of the detector coil drops significantly (Q factor 48 b) comparedto when the power supply apparatus 10 is not present (Q factor 48 a).For this reason, the Q factor of the detector coil does not changesignificantly even when foreign metal is disposed (Q factors 48 b and 48c), and thus the foreign metal detection accuracy worsens considerablyin the case of using a spiral-shaped coil as the detector coil.

According to the first embodiment described above, applying a figure8-shaped coil to the detector coil in a contactless power supply systemequipped with a foreign matter detecting apparatus greatly improvesfactors such as magnetic flux leakage from the detector coil, change inthe electrical properties (electrical parameters) due to externalfactors, and unwanted noise produced in the detector coil. Thus, itbecomes possible to detect foreign metal or other foreign matter whichmay generate heat due to magnetic flux without providing an additionalsensor, and furthermore greatly improve detection accuracy.

The present embodiment is described using an example of detectingforeign matter while contactless power supply is in operation. However,an embodiment of the present disclosure is not limited only to suchcases, and various modifications are possible. For example, it is alsoconceivable that contactless power supply operation may be suspended orthat power supplied by contactless power supply may be restricted whiledetecting foreign matter.

Since the unwanted noise produced in the detector coil decreases in suchcases, it is not strictly necessary to make the frequency of the ACsignal flowing through the detector coil differ from the frequencies ofthe AC signals flowing through the transmitter coil and the receivercoil. In other words, foreign matter detection may be conducted using anAC signal whose frequency is approximately equal to the frequencies(f1≈f2) of the AC signals used for contactless power supply operation.Also, in such cases particularly it is also possible to make thedetector coil the same as the transmitter coil or the receiver coil.

[Modification 1]

Although the foregoing first embodiment is described only for the caseof using a continuous figure 8-shaped detector coil as illustrated inFIGS. 6A, 6B, 7A and 7B, a figure 8-shaped detector coil (magneticcoupling element) like that illustrated in FIG. 14 may also be used.

In the example in FIG. 14, a figure 8-shaped detector coil L3′ includesspiral-shaped coils L31 and L32, with one end of the coil L31 beingelectrically connected (joined) in series to one end of the coil L32using solder or a connector, for example. However, the coils L31 and L32are connected such that the magnetic flux (magnetic field lines)produced from the coil L31 and the magnetic flux (magnetic field lines)produced from the coil L32 have approximately opposing orientations, asillustrated by FIG. 10B and the example in FIG. 14.

Note that this connection may also be an electrical parallel connectionor a combined series and parallel connection.

For example, in the case of an electrical series connection, voltage maybe measured using a lead 51 from the coil L31 and a lead 52 from thecoil L32. In the case of an electrical parallel connection, voltage maybe measured between the junction 53 of the coil L31 and the lead 51 orbetween the junction 53 of the coil L32 and the coil L32, taking thejunction 53 between the coil L31 and the coil L32 as a referencepotential point.

According to the present modification, since simple spiral-shaped coilsare joined to constitute a figure 8-shaped detector coil, the electricalproperties of the two coils may be easily made nearly equal compared toa continuous figure 8-shaped coil.

Although the foregoing describes an example of the case of applying asingle magnetic coupling element (figure 8-shaped coil) made up of twocoils to a detector coil as an example of the first embodiment of thepresent disclosure, the present disclosure is not limited to theforegoing embodiment, and various modifications are possible.

For example, in some cases it may be desirable to use one or multiplemagnetic coupling elements shaped like multiple coils electricallyconnected together, in order to improve foreign matter detectionaccuracy, for example.

In other words, in order to further improve foreign matter detectionaccuracy, for example, it may be more desirable to use one or multiplemagnetic coupling elements shaped like multiple coils electricallyconnected together, in which the magnetic flux produced from at leastone or more of these multiple coils and the magnetic flux produced fromthe remaining of these multiple coils have approximately opposingorientations.

Hereinafter, examples of other embodiments of the present disclosurewill be described with reference to the drawings. Note that structuralelements like those of the first embodiment are denoted with the samereference numerals, and repeated explanation of these structuralelements is omitted.

<3. Second Embodiment>

The configuration is not limited to a figure 8-shaped coil according tothe first embodiment, and a square grid-shaped (in other words, a 2×2lattice-shaped) coil may also be used as a detector coil (magneticcoupling element). Hereinafter, an example applying a square grid-shapedcoil to the detector coil will be described as a second embodiment ofthe present disclosure.

FIG. 15 is a plan view illustrating an exemplary configuration of asquare grid-shaped detector coil according to the second embodiment ofthe present disclosure.

The square grid-shaped detector coil L3A includes four spiral-shapedcoils L31 to L34 electrically connected (joined) in series. The coilsL33 and L34 have a mostly similar configuration to the spiral-shapedcoils L31 and L32. The coil L31 includes a lead 51, while the coil L34includes a lead 52. The coil L32 and the coil L33 do not have leads, andare electrically connected to their respectively adjacent coils L31 andL34. In the detector coil L3A in this example, the coils L31 to L34 areconnected such that the magnetic flux (magnetic field lines) producedfrom the coils L31 and L33 is of approximately opposite orientation tothe magnetic flux (magnetic field lines) produced from the coils L32 andL34 at a given time (phase).

Note that this connection may also be an electrical parallel connectionor a combined series and parallel connection, similarly to the examplein FIG. 14.

In the present embodiment, it is likewise desirable for the relationshipbetween the inner dimension A or the outer dimension B of the detectorcoil L3A and the receiver coil to be the relationship described in thefirst embodiment.

According to the foregoing second embodiment, action and advantages likethe following are obtained in addition to the action and advantages ofthe first embodiment.

A detector coil according to the second embodiment is a squaregrid-shaped coil including four coils. Increasing the number of coilscompared to the figure 8-shaped coil according to the first embodimentincreases the surface area occupied by the detector coil and increasesthe detection range. For example, in the case of a detector coilaccording to the second embodiment, the detection range may be doubledcompared to a detector coil of the first embodiment.

However, since a detector coil of the first embodiment has betterdetection accuracy, the decision to implement the first embodiment orthe second embodiment may be determined according to whether detectionaccuracy or detection range is prioritized.

[Modification 1]

FIG. 16 is a plan view illustrating an exemplary configuration of asquare grid-shaped detector coil according to a first modification ofthe second embodiment of the present disclosure.

The square grid-shaped detector coil L3B differs from the detector coilL3A in that the coils constituting the detector coil L3B are connectedsuch that the magnetic flux (magnetic field lines) produced from thecoils L31 and L34′ on which leads 51 and 52 are formed is ofapproximately opposite orientation to the magnetic flux (magnetic fieldlines) produced from the coils L32 and L33′ at a given time (phase).

Note that this connection may also be an electrical parallel connectionor a combined series and parallel connection, similarly to the examplein FIG. 14.

<4. Third Embodiment>

The configuration is not limited to a square grid-shaped coil accordingto the above second embodiment, and a lattice-shaped coil may also beused as a detector coil (magnetic coupling element). Hereinafter, anexample applying a lattice-shaped coil to the detector coil will bedescribed as a third embodiment of the present disclosure.

FIG. 17 is a plan view illustrating an exemplary configuration of alattice-shaped detector coil according to the third embodiment of thepresent disclosure. The lattice-shaped detector coil L3C is configuredsuch that multiple coils are connected in an electrical seriesconnection, parallel connection, or a combined series and parallelconnection. The example in FIG. 17 is for the case of a detector coilthat includes 21 spiral-shaped coils L31 to L321 connected in series.

In the detector coil L3C, the coils L31 to L321 are disposed in a matrixparallel to the plane of the magnetic shielding material 41, forexample, with the coils from the coil L31 to the coil L321 beingcontinuously connected in sequence. For example, the coils L31 to L37may be connected from left to right, with the coils L38 to L314connected from right to left on the next row down, and the coils L315 toL321 connected from left to right one more row down. The coils L31 toL321 are connected such that the magnetic flux (magnetic field lines)produced from adjacent coils are of approximately opposing orientationsat a given time (phase).

In this way, a detector coil may be configured such that multiple coilssuch as spiral-shaped coils, helical coils, or coils with a combinedspiral and helical shape (in other words, coils having a basic ringshape) are connected in an electrical series connection, parallelconnection, or a combined series and parallel connection. However, it isdesirable for these multiple coils constituting the detector coil to beconnected such that the magnetic flux (magnetic field lines) producedfrom at least one or more of these multiple coils and the magnetic flux(magnetic field lines) produced from the remaining of these multiplecoils have approximately opposing orientations at a given time (phase).

Also, in the case where the detector coil includes multiple coils, it isparticularly desirable for the total magnetic flux (magnetic fieldlines) produced from at least one or more coils to be approximatelyequal to the total magnetic flux (magnetic field lines) of approximatelyopposite orientation produced from the remaining coils. In this case,issues such as magnetic flux leakage from the detector coil, changes inthe electrical properties (electrical parameters) of the detector coildue to external factors, and unwanted noise occurring in the detectorcoil decrease particularly. In order to equalize the total magneticflux, it is desirable for there to be an even number of coilsconstituting the detector coil in the case where each of the multiplecoils has approximately the same shape.

Furthermore, it is desirable for the number of coils producing magneticflux (magnetic field lines) of approximately opposite orientation to behalf the number of coils constituting the detector coil. In this case,since the magnetic flux distribution within the detector coil becomesapproximately uniform, foreign metal detection accuracy stabilizes.

Meanwhile, it is desirable for at least one or more coils from among themultiple coils constituting the detector coil to have an inner dimensionthat is smaller than the inner dimension of the transmitter coil or thereceiver coil.

In addition, it is desirable for the overall inner dimension of themultiple coils constituting the detector coil to be smaller than theinner dimension of the transmitter coil or the receiver coil. Theoverall inner dimension of the multiple coils constituting the detectorcoil may be either the inner dimension A along the shorter edge or theinner dimension A′ along the longer edge, as illustrated in FIG. 17.

Furthermore, it is particularly desirable for the overall outerdimension of the detector coil to be smaller than the inner dimension ofthe transmitter coil or the receiver coil.

These parameters are for decreasing change in the electrical properties(such as the Q factor and L value) of the detector coil due to externalfactors. Also, in order to effectively suppress unwanted noise producedin the detector coil, it is desirable for the shape of the detector coilto be an approximately symmetrical shape, such as by having approximaterotational symmetry, approximate line symmetry, or approximate pointsymmetry. However, the configuration is not limited thereto in the casewhere it is desirable to extend the foreign metal detection range evenif the foreign metal detection accuracy drops.

According to the third embodiment discussed above, the number of coilsconstituting the detector coil is further increased compared to thesecond embodiment, and thus the detection range of the detector coil issignificantly extended.

<5. Fourth Embodiment>

Although the foregoing first through third embodiments are described forthe case of providing one detector coil, an embodiment of the presentdisclosure is not limited to such a case, and may also be configuredsuch that two or more detector coils (magnetic coupling elements) aremultiply provided, as illustrated in FIGS. 18 and 19, for example.Correspondingly, the foreign matter detecting apparatus 31 may also bemultiply provided. Alternatively, it may be configured such that one ormultiple foreign matter detecting apparatus are able to switch amongmultiply disposed detector coils.

FIG. 18 is a plan view of a detector coil unit 61 in which two figure8-shaped detector coils are disposed according to the fourth embodimentof the present disclosure.

In the detector coil unit 61 in this example, two detector coils L3-1and L3-2 are disposed adjacent to each other on the sides which areopposite the sides having their respective leads 51 and 52. The detectorcoils L3-1 and L3-2 each have a configuration similar to the detectorcoil L3′, with a single detector coil including two spiral-shaped coils.However, the detector coil unit 61 in this example obviously may also beconfigured using the detector coil L3.

Herein, the respective conductive lines of the detector coil L3-1 andthe detector coil L3-2 may also be disposed overlapping by a givenamount. By disposing the detector coil L3-1 and the detector coil L3-2in this way, their detection ranges overlap, which resolves the problemof a dead zone between the detector coil L3-1 and the detector coil L3-2where foreign matter is not detected.

[Modification 1]

FIG. 19 is a plan view illustrating a detector coil unit in which twofigure 8-shaped detector coils are disposed according to a firstmodification of the fourth embodiment of the present disclosure.

In the detector coil unit 62 in this example, two detector coils L3-1and L3-2′ are disposed adjacent to each other on the sides which areopposite the sides having their respective leads 51 and 52. The coilL31′ and the coil L32′ of the detector coil L3-2′ have a magnetic flux(magnetic field lines) orientation that is the reverse of the coil L31and the coil L32 of the detector coil L3-2.

Meanwhile, in the multiple detector coils illustrated in FIGS. 18 and19, it is desirable for at least one or more coils from among themultiple coils constituting each detector coil to have an innerdimension that is smaller than the inner dimension of the transmittercoil or the receiver coil.

In addition, it is desirable for the overall inner dimension of themultiple coils constituting the multiple detector coils to be smallerthan the inner dimension of the transmitter coil or the receiver coil.

Furthermore, it is particularly desirable for the overall outerdimension of the multiple detector coils to be smaller than the innerdimension of the transmitter coil or the receiver coil.

The above is for decreasing change in the electrical properties (such asthe Q factor and L value) of the detector coil due to external factors.

Also, in order to effectively suppress unwanted noise produced in themultiple detector coils, it is desirable for the multiple detector coilsto be disposed so as to form an approximately symmetrical shape, such asby having approximate rotational symmetry, approximate line symmetry, orapproximate point symmetry. However, the configuration is not limitedthereto in the case where it is desirable to extend the foreign metaldetection range even if the foreign metal detection accuracy drops.

According to the fourth embodiment discussed above, a single foreignmatter detecting apparatus is provided with respect to a detector coilunit having multiple detector coils (magnetic coupling elements), suchthat multiple detector coils may be used by switching among them in atime division. Also, multiple foreign matter detecting apparatus may beprovided such that one of the multiple detector coils may be used as amain detector coil while using the remaining detector coils as auxiliarydetector coils.

Note that in the case where the outer dimension across one or multipledetector coils made up of multiple coils is greater than the innerdimension of the receiver coil (or the transmitter coil), it may bedifficult to dispose part or all of the one or multiple detector coilsin the same plane as the receiver coil (or the transmitter coil). Insuch cases, it is anticipated that a magnetic or other material may bedisposed between all or at least part of the one or multiple detectorcoils and the receiver coil (or the transmitter coil). This is in orderto mitigate drops in the Q factor of the one or multiple detector coilsin the case where the one or multiple detector coils are disposed on topof the winding part or the pattern part of the receiver coil (or thetransmitter coil).

<6. Fifth Embodiment>

Next, an example in which a receiver coil and multiple detector coils(magnetic coupling elements) are disposed outside the same plane will bedescribed as a fifth embodiment of the present disclosure.

FIGS. 20A to 20C are explanatory diagrams for an exemplary detector coilarrangement according to the fifth embodiment of the present disclosure.FIGS. 20A, 20B, and 20C are plan views illustrating an example of areceiver coil, an example in which multiple detector coils are disposedon top of the receiver coil, and an example in which some detector coilsare disposed in the center of the receiver coil, respectively.

In the receiver 22A illustrated in FIG. 20A, a receiver coil L2 isdisposed on top of magnetic shielding material 41 (FIG. 20A), withdetector coils L3-1 to L3-4, for example, disposed on top of thereceiver coil L2 via magnetic material 65.

The receiver coil L2 is formed by multiply winding conductive wire in aspiral shape (such as an approximately circular shape, an approximatelyelliptical shape, or an approximately rectangular shape) in the sameplane. In this example, conductive wire is wound in an approximatelysquare spiral. Along each of the four edges of the approximately squarereceiver coil L2, there is placed magnetic material 65 of approximatelythe same size as the horizontal and vertical Feret diameters (projectionwidths) of the detector coils L3-1 to L3-4. Additionally, the detectorcoils L3-1 to L3-4 are disposed on top of the respective magneticmaterial 65.

The detector coils L3-1 to L3-4 may be four continuously connectedfigure 8-shaped coils, or split into multiple detector coils, asillustrated in FIGS. 15 to 19.

Experiment has confirmed that foreign metal may be detected with theforegoing fifth embodiment, similarly to the second through fourthembodiments, even in the case where the receiver coil and the detectorcoil are disposed outside the same plane, or in other words, even whennot disposed on the same plane in the Z direction.

Note that although it is desirable to dispose magnetic material betweenthe receiver coil L2 and the detector coils L3-1 to L3-4 as illustratedin FIG. 20B in order to mitigate drops in the Q factor of the detectorcoils, the configuration is not limited thereto.

In addition, a receiver 22A′ may also be configured by disposingdetector coils in the center of the receiver coil L2, as illustrated inFIG. 20C. In this case, it is also conceivable to dispose some of thedetector coils (such as the detector coils L3A in FIG. 20C, for example)in the same plane as the receiver coil L2, while disposing the remainingdetector coils outside the same plane as the receiver coil L2.Obviously, all detector coils may also be disposed outside the sameplane as the receiver coil L2.

<7. Sixth Embodiment>

Next, exemplary countermeasures for the case where foreign metalgenerates heat over a wide range will be described as the sixthembodiment of the present disclosure.

FIG. 21A and FIG. 21B are explanatory diagrams for an exemplary detectorcoil (magnetic coupling element) arrangement according to the sixthembodiment of the present disclosure. FIGS. 21A, 21B, and 21C are planviews illustrating an example of a receiver coil and foreign metal, anexample in which multiple detector coils are disposed on top of thereceiver coil, and an example in which multiple detector coils areadditionally disposed on top of the multiple detector coils in FIG. 21B,respectively.

As illustrated in FIG. 21A, it is conceivable that foreign metal 70 maygenerate heat over a wide area on the outside of the receiver coil L2(the area enclosed by broken lines). In cases where foreign metalgenerates heat over a wide area in this way, it is conceivable todispose multiple detector coils over a wide area as a countermeasure.

In the receiver 22B illustrated in FIG. 21B, 10 figure 8-shaped detectorcoils L3-1-1 to L3-10-1, for example, are disposed on top of thereceiver coil L2. The overall horizontal and vertical Feret diameters ofthese 10 detector coils are greater than the receiver coil L2. In FIG.21B, the detector coils are alternately shaded and unshaded in order todistinguish between adjacent figure 8-shaped detector coils.

However, in the case of the exemplary arrangement in FIG. 21B, a deadzone where foreign metal is not detected may exist between a givendetector coil and an adjacent detector coil. For this reason, in somecases it may also be desirable to dispose detector coils in two or morelayers, like in the exemplary arrangement in FIG. 21C. Herein, areceiver 22B′ is configured by disposing 10 detector coils L3-1-1 toL3-10-1 (the first layer) on top of the receiver coil L2, andadditionally disposing 10 more detector coils L3-1-2 to L3-10-2 (thesecond layer) on top of the first layer.

At this point, the problem of a dead zone between adjacent detectorcoils may be resolved by disposing the second layer of detector coilsshifted by ½ pitch with respect to the first layer of detector coils.Also, if the figure 8-shaped detector coils in the first layer arearranged vertically (in the Y direction) and the detector coils in thesecond layer are arranged horizontally (in the X direction), it ispossible to detect magnetic flux changes in a different direction thanthe first layer of detector coils, thus reliably resolving the dead zoneproblem and improving foreign metal detection accuracy.

According to the foregoing sixth embodiment, it is possible to detectforeign metal over a wide range of the receiver coil. Also, by disposingthe detector coils in two or more layers, it becomes possible to resolvethe problem of dead zones where foreign metal is not detected.

[Modification 1]

FIG. 22A and FIG. 22B are explanatory diagrams for exemplary detectorcoil arrangements according to a first modification of the sixthembodiment of the present disclosure. FIGS. 22A and 22B are plan viewsillustrating an example in which multiple detector coils are disposed ontop of the receiver coil, and an example in which multiple detectorcoils are additionally disposed on top of the multiple detector coils inFIG. 22A, respectively.

Whereas detector coils are disposed in the horizontal and verticaldirections of the receiver 22B according to the sixth embodimentillustrated in FIG. 21A and FIG. 21B, detector coils are disposed in thediagonal direction of the receiver coil in the example illustrated inFIG. 22A and FIG. 22B.

In the receiver 22C illustrated in FIG. 22B, nine figure 8-shapeddetector coils L3-1-1 to L3-9-1, for example, are disposed on top of thereceiver coil L2 in the diagonal direction of the approximately squarereceiver coil L2. The overall horizontal and vertical Feret diameters ofthese nine detector coils are greater than the receiver coil L2. In FIG.22B, the detector coils are alternately unshaded, shaded gray, andshaded black in order to distinguish between adjacent figure 8-shapeddetector coils.

Also, in order to resolve the problem of a dead zone between adjacentdetector coils, a receiver 22C′ is configured by disposing a first layerof detector coils L3-1-1 to L3-9-1 on top of the receiver coil L2, anddisposing a second layer of detector coils L3-1-2 to L3-9-2 on top ofthe first layer. At this point, the second layer of detector coilsL3-1-2 to L3-9-2 are disposed in a different diagonal direction thanthat of the first layer of detector coils L3-1-1 to L3-9-1.

According to this example, a second layer of detector coils is disposedin a different diagonal direction that that of the first layer ofdetector coils, thereby making it possible to detect magnetic fluxchanges in a different direction than the first layer of detector coils,and thus reliably resolving the dead zone problem and improving foreignmetal detection accuracy.

<8. Other>

The foregoing first through sixth embodiments are described for the caseof providing a foreign matter detecting apparatus including one or moredetector coils in an electronic device given as a secondary device(power recipient device).

However, an embodiment of the present disclosure is not limited to sucha case, and may also be configured such that a foreign matter detectingapparatus including one or more detector coils is provided in a powersupply apparatus given as a primary device. In such cases, the receivercoil described in the foregoing first embodiment may be substituted witha transmitter coil, and the transmitter coil may be substituted with areceiver coil. A foreign matter detecting apparatus including one ormore detector coils may also be disposed in both a primary device and asecondary device.

Furthermore, it may also be configured such that a foreign matterdetecting apparatus including one or more detector coils is provided inanother apparatus separate from a primary device and a secondary device.

In other words, it may be configured such that the foreign matterdetecting apparatus including one or more detector coils described inthe foregoing embodiments is provided in at least one of a primarydevice, a secondary device given as a power recipient device, or anotherapparatus separate from the primary device and the secondary device.

Also, in the description of the foregoing embodiments, there isdescribed the example of a system (such as a foreign matter detectingapparatus, for example) that detects the presence of foreign matter fromchange in the Q factor of a magnetic coupling element (detector coil),or from change in the Q factor of an LC resonator (resonant circuit)that at least includes a magnetic coupling element. However, the abovesystem is not limited to such an example, and may also be a foreignmatter detection system that detects the presence of foreign matterusing a separate technique related to a magnetic coupling element.

For example, a case is also conceivable in which foreign matter isdetected on the basis of other electrical parameters which arecalculated (estimated, indirectly measured) on the basis of measurementresults for the Q factor of a magnetic coupling element, or measurementresults for the Q factor of an LC resonator (resonant circuit) that atleast includes a magnetic coupling element.

Also conceivable is a case in which foreign matter is detected on thebasis of changes in some kind of electrical property (electricalparameter) related to an individual magnetic coupling element, or to anapparatus and system that utilize a magnetic coupling element. Potentialexamples of such an electrical property (electrical parameter) include apower value, a voltage value, a current value, a power factor, an energyefficiency, a power supply efficiency, a charging efficiency, an energyloss, the amplitude, phase, period, pulse width, or duty cycle of adetection signal, an impedance value, a mutual inductance value, acoupling coefficient, a magnetic flux magnitude, a magnetic fluxdensity, a capacitance value, a self-inductance value, a resonantfrequency, a carrier wave frequency, a signal wave frequency, amodulation factor, a signal level, a noise level, and a temperature, forexample.

Additionally, it is also conceivable that in a foreign matter detectionsystem according to an embodiment of the present disclosure, multipleforeign matter detection techniques rather than just one of the foreignmatter detection techniques discussed above may be combined and utilizedjointly.

Although the foregoing embodiments are described only for the case ofproviding one transmitter coil and receiver coil each, an embodiment ofthe present disclosure is not limited to such a case, and may also beconfigured such that multiple (two or more) transmitter coils orreceiver coils are provided, for example.

In addition, other LC resonators (resonant circuits) besides the LCresonator (resonant circuit) discussed earlier may be used in acontactless power supply system (for contactless power supplyfunctionality or foreign matter detection functionality).

Also, although in the foregoing embodiments each coil (transmitter coil,receiver coil, detector coil) is taken to be spiral-shaped (planar) orhelically wound in the direction of thickness, an embodiment of thepresent disclosure is not limited to such examples. For example, eachcoil may also have an alpha-winding shape in which a spiral-shaped coilfolds back on itself in two layers, or spiral shapes with additionallayers, for example.

The transmitter coil and receiver coil may also be configured with acoil whose shape enables reduced magnetic flux leakage, such as a figure8 shape, a square grid shape, or a lattice shape.

The detector coil may also be integrated with a transmitter coil or areceiver coil, and a contactless power supply coil such as a transmittercoil or a receiver coil may be jointly used as a detector coil.Moreover, a coil used for purposes other than contactless power supply,such as an induction heating coil or a wireless communication coil mayalso be jointly used as a detector coil.

In other words, although the foregoing embodiments are described usingthe example of the case where a magnetic coupling element is taken to bea detector coil, it is also conceivable for the magnetic couplingelement to be a coil such as a coil for contactless power supply (atransmitter coil or a receiver coil), an induction heating coil, or awireless communication coil, such that these coils are also used for thepurpose of detecting foreign matter.

Also, material such as magnetic material or metal material may also beprovided in the transmitter of the power transmitting apparatus, in thereceiver of the power receiving apparatus, and in the vicinity of theone or more detector coils, for the purpose of mitigating unwantedmagnetic flux (magnetic field lines; magnetic field) leakage andimproving transfer efficiency (power supply efficiency), for example.

Also, the respective resonant capacitors (particularly the resonantcapacitor in the foreign matter detecting apparatus) are not limited tothe case of using fixed capacitance values, and may also be configuredwith variable electrostatic capacitance values (such as a configurationthat uses switches or other components to switch among connectionpathways for multiple capacitive elements, for example). Configuring theresonant capacitors in this way makes it possible to control (optimize)the resonant frequency by adjusting the electrostatic capacitancevalues.

In addition, although the foregoing embodiments are described withreference to specific components of a power supply apparatus and anelectronic device, for example, it is not necessary to provide all ofthe components, and furthermore, other components may be additionallyprovided. For example, it may also be configured such that a powersupply apparatus (power transmitting apparatus) or an electronicapparatus (power receiving apparatus) is provided with communicationfunctionality, some kind of detection functionality, controlfunctionality, display functionality, functionality for authenticating asecondary device, functionality for determining that a secondary deviceis on top of a primary device, and functionality for detecting thepresence of foreign matter according to a different technique than thataccording to an embodiment of the present disclosure, for example.

Also, although the foregoing embodiments are described by taking anexample for the case of using load modulation for communicationfunctionality, an embodiment of the present disclosure is not limited tosuch a case. For example, a modulation technique other than loadmodulation may also be used for communication functionality, orcomponents such as a wireless communication antenna or wirelesscommunication coil may be provided to communicate according to atechnique other than modulation. Meanwhile, depending on theconfiguration of the contactless power supply functionality (the powertransmitting apparatus and the power receiving apparatus) and theforeign matter detection functionality (the foreign matter detectingapparatus), it may also be configured such that communicationfunctionality itself is not provided. Similarly, depending on theconfiguration of the contactless power supply functionality (the powertransmitting apparatus and the power receiving apparatus) and theforeign matter detection functionality (the foreign matter detectingapparatus), it may also be configured such that portions of the variouscomponents (such as parts, units, and circuits) used in the descriptionof the foregoing embodiments are not provided.

Also, although the foregoing embodiments are described by taking aexample for the case where multiple (two) electronic devices areprovided in a contactless power supply system, an embodiment of thepresent disclosure is not limited to such an example, and one electronicdevice, or three or more electronic devices, may also be provided in thecontactless power supply system.

Furthermore, although the foregoing embodiments are described by takinga charging tray for portable electronic devices (CE devices) such asmobile phones as an example of a power supply apparatus, the powersupply apparatus is not limited to such consumer charging trays, and isapplicable as a charging device for various types of electronic devices.Moreover, it is not strictly necessary for the power supply apparatus tobe a tray, and may also be a stand for an electronic device, such as acradle, for example.

Also, although the foregoing embodiments are described by taking anelectronic device as an example of a power recipient device, the powerrecipient device is not limited thereto, and may also be a powerrecipient device other than an electronic device (such as an electriccar or other vehicle, for example).

Additionally, the present technology may also be configured as below.

(1) A detecting apparatus including:

one or a plurality of magnetic coupling elements that include aplurality of coils; and

a detector that measures an electrical parameter related to the one orplurality of magnetic coupling elements or to a circuit that at leastincludes the one or plurality of magnetic coupling elements, anddetermines from a change in the electrical parameter whether a foreignmatter that generates heat due to magnetic flux is present,

wherein, in the one or plurality of magnetic coupling elements, theplurality of coils are electrically connected such that magnetic fluxproduced from at least one or more of the plurality of coils andmagnetic flux produced from remaining coils of the plurality of coilshave approximately opposing orientations.

(2) The detecting apparatus according to (1), wherein the electricalparameter is a Q factor of the one or plurality of magnetic couplingelements or of a circuit that at least includes the one or plurality ofmagnetic coupling elements.

(3) The detecting apparatus according to (1) or (2), wherein

a dimension of an innermost perimeter of at least one or more coils fromamong the plurality of coils included in the one or plurality ofmagnetic coupling elements is smaller than a dimension of an innermostperimeter of a contactless power supply coil used for contactless powersupply.

(4) The detecting apparatus according to (3), wherein

a dimension of an outermost perimeter of at least one or more coils fromamong the plurality of coils included in the one or plurality ofmagnetic coupling elements is smaller than the dimension of theinnermost perimeter of the contactless power supply coil.

(5) The detecting apparatus according to any one of (1) to (4), wherein

a center point of the one or plurality of magnetic coupling elements anda center point of the contactless power supply coil are positioned onapproximately a same axis.

(6) The detecting apparatus according to any one of (3) to (5), wherein

a total area of regions inside innermost perimeters of the plurality ofcoils included in the one or plurality of magnetic coupling elements issmaller than an area of a region inside the innermost perimeter of thecontactless power supply coil.

(7) The detecting apparatus according to any one of (4) to (6), wherein

a total area of regions inside outermost perimeters of the plurality ofcoils included in the one or plurality of magnetic coupling elements issmaller than an area of a region inside the innermost perimeter of thecontactless power supply coil.

(8) The detecting apparatus according to any one of (1) to (7), wherein

a total magnetic flux of approximately a same orientation and a totalmagnetic flux of approximately an opposite orientation that are producedfrom the plurality of coils included in the one or plurality of magneticcoupling elements are approximately identical.

(9) The detecting apparatus according to any one of (1) to (8), wherein

a number of the plurality of coils included in the one or plurality ofmagnetic coupling elements is even.

(10) The detecting apparatus according to any one of (1) to (9), wherein

the plurality of coils included in at least one magnetic couplingelement from among the one or plurality of magnetic coupling elementsare disposed in a FIG. 8 shape, a square grid shape, or a lattice shape.

(11) The detecting apparatus according to any one of (1) to (10),wherein

the plurality of coils included in the one or plurality of magneticcoupling elements are electrically connected in a series connection, aparallel connection, or a combined series and parallel connection.

(12) The detecting apparatus according to any one of (1) to (11),wherein

the one or plurality of magnetic coupling elements are disposed in asymmetrical shape having any of rotational symmetry, line symmetry, orpoint symmetry.

(13) The detecting apparatus according to any one of (1) to (12),wherein

the one or plurality of magnetic coupling elements and a contactlesspower supply coil used for contactless power supply are disposed onapproximately a same plane.

(14) The detecting apparatus according to any one of (1) to (13),wherein

a contactless power supply coil used for contactless power supply is atransmitter coil provided in a power source device, or a receiver coilprovided in a power recipient device.

(15) The detecting apparatus according to any one of (1) to (14),wherein

the circuit that at least includes the one or plurality of magneticcoupling elements is a resonant circuit.

(16) A power receiving apparatus including:

a receiver coil used for contactless power supply from a power source;

one or a plurality of magnetic coupling elements that include aplurality of coils; and

a detector that measures an electrical parameter related to the one orplurality of magnetic coupling elements or to a circuit that at leastincludes the one or plurality of magnetic coupling elements, anddetermines from a change in the electrical parameter whether a foreignmatter that generates heat due to magnetic flux is present,

wherein, in the one or plurality of magnetic coupling elements, theplurality of coils are electrically connected such that magnetic fluxproduced from at least one or more of the plurality of coils andmagnetic flux produced from remaining coils of the plurality of coilshave approximately opposing orientations.

(17) A power transmitting apparatus including:

a transmitter coil used for contactless power supply for a powerrecipient;

one or a plurality of magnetic coupling elements that include aplurality of coils; and

a detector that measures an electrical parameter related to the one orplurality of magnetic coupling elements or to a circuit that at leastincludes the one or plurality of magnetic coupling elements, anddetermines from a change in the electrical parameter whether a foreignmatter that generates heat due to magnetic flux is present,

wherein, in the one or plurality of magnetic coupling elements, theplurality of coils are electrically connected such that magnetic fluxproduced from at least one or more of the plurality of coils andmagnetic flux produced from remaining coils of the plurality of coilshave approximately opposing orientations.

(18) A contactless power supply system including:

a power transmitting apparatus that wirelessly transmits power; and

a power receiving apparatus that receives power from the powertransmitting apparatus,

wherein at least one of the power transmitting apparatus or the powerreceiving apparatus includes

one or a plurality of magnetic coupling elements that include aplurality of coils, and

a detector that measures an electrical parameter related to the one orplurality of magnetic coupling elements or to a circuit that at leastincludes the one or plurality of magnetic coupling elements, anddetermines from a change in the electrical parameter whether a foreignmatter that generates heat due to magnetic flux is present, and

wherein, in the one or plurality of magnetic coupling elements, theplurality of coils are electrically connected such that magnetic fluxproduced from at least one or more of the plurality of coils andmagnetic flux produced from remaining coils of the plurality of coilshave approximately opposing orientations.

Note that the series of operations in the foregoing embodiments may beexecuted in hardware, and may also be executed in software. In the caseof executing the series of operations in software, a programconstituting such software may be executed by a computer built intospecial-purpose hardware, or alternatively, by a computer onto whichprograms for executing various functions are installed. For example, aprogram constituting the desired software may be installed and executedon a general-purpose personal computer.

Also, a recording medium storing program code of software that realizesthe functionality of the foregoing embodiments may also be supplied to asystem or apparatus. It is furthermore obvious that the functionality isrealized by a computer (or CPU or other control apparatus) in such asystem or apparatus retrieving and executing the program code stored inthe recording medium.

The recording medium used to supply program code in this case may be aflexible disk, hard disk, optical disc, magneto-optical disc, CD-ROM,CD-R, magnetic tape, non-volatile memory card, or ROM, for example.

Also, the functionality of the foregoing embodiments may realized by acomputer executing retrieved program code. In addition, some or all ofthe actual operations may be conducted on the basis of instructions fromsuch program code by an OS or other software running on the computer.This also encompasses cases where the functionality of the foregoingembodiments is realized by such operations.

Also, in this specification, the processing steps stating operations ina time series obviously encompass operations conducted in a time seriesfollowing the described order, but also encompass operations executed inparallel or individually (by parallel processing or object-orientatedprocessing, for example), without strictly being processed in a timeseries.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

In other words, since the foregoing exemplary embodiments are ideal,specific examples of the present disclosure, various technicallypreferable limitations have been imposed thereon. However, the technicalscope of the present disclosure it not to be limited to theseembodiments, unless statements that particularly limit the presentdisclosure are made in their respective descriptions. For example,factors such as the types and quantities of materials used, processingtimes, processing sequences, and numerical conditions for respectiveparameters cited in the foregoing description are merely idealizedexamples. Furthermore, the dimensions, shapes, and positionalrelationships illustrated in the drawings used in the description aregeneral and diagrammatic.

What is claimed is:
 1. A power transmitting apparatus, comprising: afirst coil in a first layer; a second coil, in a second layer, thatoverlaps the first coil; and a third coil, in a third layer, thatoverlaps the first coil and the second coil, wherein the third coilcomprises a first sub coil, a second sub coil, a third sub coil, and afourth sub coil that are connected in series, the first sub coil and thethird sub coil produce a first magnetic flux in a first orientation, andthe second sub coil and the fourth sub coil produce a second magneticflux in a second orientation, wherein the first orientation is differentfrom the second orientation, and wherein an outer end of the first subcoil is connected to an outer end of the second sub coil, and an innerend of the second sub coil is connected to an inner end of the third subcoil.
 2. The power transmitting apparatus according to claim 1, whereinthe first coil is configured to wirelessly supply power to a powerreceiving apparatus.
 3. The power transmitting apparatus according toclaim 2, wherein the power transmitting apparatus and the powerreceiving apparatus are linked based on electromagnetic induction. 4.The power transmitting apparatus according to claim 2, wherein at leastone of the first coil, the second coil, or the third coil has at leastone of a rotational symmetry, a line symmetry, or a point symmetry. 5.The power transmitting apparatus according to claim 1, wherein thesecond coil is configured to wirelessly supply power to a powerreceiving apparatus.
 6. The power transmitting apparatus according toclaim 1, wherein the third coil is configured to wirelessly supply powerto a power receiving apparatus.
 7. The power transmitting apparatusaccording to claim 1, wherein at least one of the first coil or thesecond coil is configured to transmit power to a power receivingapparatus.
 8. The power transmitting apparatus according to claim 1,wherein at least one of the first coil, the second coil, or the thirdcoil is configured to detect a foreign matter between the powertransmitting apparatus and a power recipient.
 9. The power transmittingapparatus according to claim 8, wherein the power transmitting apparatusis configured to detect a change in Q factor of at least one of thefirst coil, the second coil, the third coil, or a circuit that includesat least one of the first coil, the second coil, or the third coil. 10.The power transmitting apparatus according to claim 9, wherein thecircuit is a resonant circuit.
 11. The power transmitting apparatusaccording to claim 1, wherein the first coil, the second coil, and thethird coil are configured to generate the first magnetic flux of thefirst orientation and the second magnetic flux of the second orientationthat is opposite to the first orientation, wherein the first magneticflux is equal to the second magnetic flux.
 12. The power transmittingapparatus according to claim 1, wherein at least one of the second coilor the third coil is in one of a shape of numeral eight, a square gridshape, or a lattice shape.
 13. The power transmitting apparatusaccording to claim 12, wherein a magnetic shielding material is betweena housing of the power transmitting apparatus and the second coil. 14.The power transmitting apparatus according to claim 1, wherein the firstcoil is configured to transmit power to a power recipient, and at leastone of the second coil or the third coil is configured to detect aforeign matter between the power transmitting apparatus and the powerrecipient.
 15. The power transmitting apparatus according to claim 1,wherein a first dimension of an innermost perimeter of the second coilis greater than a second dimension of an innermost perimeter of thethird coil.
 16. A contactless power supply system, comprising: a powertransmitting apparatus configured to wirelessly transmit power; and apower receiving apparatus configured to receive the power from the powertransmitting apparatus, wherein at least one of the power transmittingapparatus or the power receiving apparatus includes: a first coil in afirst layer; a second coil, in a second layer, that overlaps the firstcoil; and a third coil, in a third layer, that overlaps the first coiland the second coil, wherein the third coil comprises a first sub coil,a second sub coil, a third sub coil, and a fourth sub coil that areconnected in series, the first sub coil and the third sub coil produce afirst magnetic flux in a first orientation, and the second sub coil andthe fourth sub coil produce a second magnetic flux in a secondorientation, wherein the first orientation is different from the secondorientation, and wherein an outer end of the first sub coil is connectedto an outer end of the second sub coil, and an inner end of the secondsub coil is connected to an inner end of the third sub coil.